Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Adds substantial detail beyond the annotations: tiles are appended to existing content rather than replacing it, all tiles land on one existing page, a second '##' is refused, and the returned view_id/tiles/parent_resource_url shapes are described. It also surfaces the precondition to read existing tile colours and continue the palette before writing, which an agent could not infer from destructiveHint/openWorldHint alone.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and result, then workflow and guidance, with no filler sentences. It runs dense in its back half with multiple resource pointers, which slightly taxes scanning but each pointer is actionable.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

All three required parameters are anchored by ISO date semantics, period values, and markdown structure mapping, plus explicit pointers to the overview and design resources. With an output schema present and the return shape still summarized, nothing needed to invoke this correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds semantics the schema does not carry — default uniform tile size, import-order appending, and the palette-continuation requirement tied to inline colour values. The heading-to-tile mapping largely duplicates the schema text, keeping this short of a 5.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource with scope: 'Append tiles generated from Markdown into your personal planner for the period containing the given date.' The 'personal planner' scope inherently separates it from the project-planner and by-view siblings, so an agent can pick correctly without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear operational context and next steps: tiles arrive at one default size in import order, arrange them via xtiles_get_page_layout then xtiles_set_page_layout, and points to the design guide for formatting decisions. It never states an explicit when-not-to-use or names the alternative markdown-import siblings, so it stops short of a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.